Please correct me if I'm wrong, but I understand this situation as follows:
So you deposit 1000 NOK and receive 1000 EUR Good deal first of all!
Lets say you do 20x 1000 NOK deposits would give you 20,000 EUR which you might have lost 15,000 EUR of, then tried to cash out 5,000 EUR which was left on the account. However, the casino was only paid 20,000 NOK ( 2,000 EUR ).
This is of course a major fuck up from the casinos side, but of course they can't pay you if this is the case?
I'm sure they are protected in their Terms for technical faults. So no complaint to the MGA or doing a PAB would help.
But to mention this with another situation in "real life"; If I withdrew 1000 NOK from an ATM in Norway and got 1000 EUR instead. I'm sure I would get convicted by a court if I didnt give the funds back to the bank. Just saying...